Horrible evening so far – I came home to discover that the dog had, at some point in the preceding hours, experienced uncontrollable diarrhea in his kennel. And my wife was in class. So, guess whose job it was to clean the crate, clean the dog, and sanitize our entire apartment? Yours truly, of course.
But let us not dwell on that, disgusting and fascinating as it is. Instead, let us talk about spaceships. What follows is an elementary introduction to the current “state of the art” of space travel – if you don’t know anything about it, then this will be a great place for you to start.
So, everyone knows about the Space Shuttle. And, a lot of people can probably recognize Soyuz from the glory days of the space race. But did you know that those ships are only two of the five (well, five and a half) capable of servicing the International Space Station? Indeed, humans are fairly awash in spaceships, and this is your one-stop-shop to get introduced to all of them! I got the idea for this post because a very special event is coming up – once the shuttle Discovery docks with ISS in a few days, all five spacecraft currently in active service will be docked at the same time.
Let us begin with the venerable Space Shuttle (technically, the Space Transportation System, or STS).
We’re now at the end of the shuttle era, but she’s been a workhorse. Capable of launching 26 tons to orbit, she’s one of the heaviest lifters ever made, and has by far the greatest payload capacity of any launch system currently available. She carries a nominal crew of five, although it only takes two to operate her and she can carry eleven in an emergency (such as a space rescue). The shuttle is a hybrid launch vehicle, an unusual combination of liquid-fueled main engines (that big, brown tank stores huge quantities of rocket fuel) and solid-fuel booster rockets.
We’ve been seeing this sort of combination for decades, so we’re used to it, but it was revolutionary when it was first designed and was controversial then and today. The solid-fuel boosters are more prone to error than liquid-fuel rockets, which led to the Challenger disaster just over 25 years ago, and debris falling off of that enormous tank destroyed Endeavor in 2003. Still, the Space Shuttle has kept Americans in space for decades, and even though it was expensive and unsafe, we still don’t have a better alternative.
Well, we have something of an alternative: the Russian Soyuz capsule.
Soyuz has been the go-to ship for the Russian space program since the beginning. The design has been improved incrementally over the last half-century, but it remains in concept the same spacecraft as when it was first launched. It can accommodate a crew of three in that spheroid module on the front, as well as the bell-shaped area directly behind it. The white module with the solar panels houses fuel and air tanks, as well as the Soyuz’ main engine. It is in that middle module that the Soyuz crew re-enters the atmosphere.
Once the shuttle is retired, the Soyuz will be the only launch system in the world capable of ferrying astronauts to and from the space station. In fact, two are kept docked there at all times to function as emergency escape pods, should the station suffer some disaster. In that case, the Soyuz would be capable of automatically undocking, manuevering in orbit, and re-entering the atmosphere. Another interesting note – unlike the American Gemini and Apollo missions, the Soyuz re-entry module lands on solid ground, not in water. This makes it much cheaper to recover, if somewhat more risk-prone.
Wait, this ship looks familiar.
It should. The Progress spacecraft is basically a Soyuz that’s not designed to carry people – it can’t split into separate modules and it can’t re-enter the atmosphere. There’s also no life support, although the cargo compartment is pressurized to allow fresh food and supplies to be carried into orbit. In fact, that’s all that Progress does – carry supplies. In order for the six crew members of ISS to survive, they need a steady supply of consumables, as well as additional fuel and parts for the station itself. It’s impractical to launch people with these supplies, so the progress was designed as an unmanned solution, performing the same duties for ISS as it did for Mir and the Salyut stations of the 1970s and 1980s. It’s not sexy, but it gets the job done.
It is, however, not the only supply ship.
The European Space Agency Automated Transfer Vehicle (whew) is an up-and-coming space freighter. It has only two operational launches compared to hundreds for each of the three preceding spacecraft, but its extremely promising. It can carry three times the cargo of a Progress, and although it can’t carry humans it was designed with a crew in mind, and new units could be adapted for habitation with minimal fuss. It’s launched from French Guinea by the ESA’s powerful Ariane 5 rocket, one of the heaviest-lifting launch systems available today, and (much like Progress or Soyuz) can use its own engines to change the orbit of the ISS if necessary.
There are a lot of interesting proposals for the future of the ATV – it can carry crew, as I said, and could also be adapted to daisy-chain with other ATVs to form mini space stations. I could also be modified to return to Earth, or to travel to the Moon if mated with a heavy-duty rocket in orbit. If the ESA ever develops their manned space program, it’s likely that the ATV or one of its derivatives would be at the heart of it.
It is, to be honest, much sexier than its Japanese equivalent.
The JAXA (Japanese Aerospace Exploration Agency) H-II Transfer Vehicle is pretty much a giant tin can with thrusters. Simpler than any of the other spacecraft that service ISS, it can’t even dock by itself – it just gets close and lets the station’s Canadarm 2 manipulator pull it in to the airlock. It may be simple, but it does its job – it can carry over twice as much cargo as Progress, it cheaper to launch, and sports a pressurized compartment.
Neither the H-II, ATV, nor Progress spacecraft are designed for re-entry. When they’re no longer useful, they’re stuffed full of the station’s garbage, undocked, and their retrorockets are fired. They fall away from the station and burn up in the atmosphere high above the remotest part of the Pacific Ocean. Not the most glamorous end for a spaceship, but just like everything else in space, it serves its purpose.
But wait, I said that there were five and a half vehicles capable of servicing the space station – what about that half?
Well, nobody who’s was following my blog a few months ago can forget the SpaceX Dragon spacecraft. She’s not yet fully operational, but she utterly aced her first test flight and is arguably ready for active duty. She can carry the same quantity of supplies as the H-II, but she’s capable of re-entering the atmosphere, docking on her own, changing her own orbit more dramatically, and most importantly, carrying people. The Dragon is NASA’s current best hope for getting people aboard ISS without purchasing space on a Soyuz launch, and I’m a huge fan of the ship. If the Apollo capsule was a Model T, then the Dragon is a GT. She’s sexy as can be, frankly, and I’m very much looking forward to seeing her in action.
So, that’s my roundup of the spacecraft that humanity has to offer. They might not be as powerful as the USS Enterprise or have all the personality of the Millenium Falcon, but they have a certain industrial sort of charm all of their own. And, of course, they’re real. You can see any of these ships in real life, and (God willing) you might even be able to get aboard one someday. And you have to crawl before you can walk – someday we will have hundreds or thousands of fusion-powered ships plying the Solar System, but getting there a long journey. These ships are all steps along that path.